Compared with a conventional cathode-ray tube (CRT) display, a flat-panel display has gradually become the main-stream in the display market for lighter and slimmer, high quality frame displays. Of the flat-panel displays, the thin-film-transistor liquid crystal display (TFT LCD) plays an essential role. However, ordinary TFT LCDs have restricted applications due to narrow visual angles.
With the feature of broader visual angles, the multi-domain vertical alignment (MVA) LCD has become a target for the display industry to achieve.
FIGS. 1A-1C are top views of an MVA LCD pixel. Transparent electrode 110 of the pixel includes four domains, wherein the four domains are interlinked. FIG. 1A shows a schematic diagram of the pixel before a voltage is applied. The liquid crystal molecules are perpendicular to the plane of the transparent electrode 110, so only one end point of the liquid crystal molecules can be seen in the top view, wherein the end point is denoted by a circular point. FIG. 1B shows a schematic diagram of the pixel after a voltage is applied. When a voltage is applied to the pixel, the liquid crystal molecules tilt toward the center of the four domains, enabling the user to view the screen frame at a broader angle of view.
FIGS. 2A-2C are top views of another MVA LCD pixel. FIG. 2A is a schematic diagram of the pixel before a voltage is applied, wherein slit 21 is disposed at the lower panel of the LCD while protrusion 22 is disposed at the upper panel of the LCD. FIG. 2B is a schematic diagram of the pixel after a voltage has been applied. When a voltage is applied to the pixel, the liquid crystal molecules tilt according to respective electric field direction and split into multiple domains.
However, when an external driving force, such as an electric field or the user's touch, is applied to the MVA LCD, mura appears on the display screen. The liquid crystal molecules, having received the external driving force, would not be aligned in accordance with original designed directions. FIG. 1C and FIG. 2C are schematic diagrams showing the pixel having received the external driving force. After receiving the external driving force, the alignment directions of the liquid crystal molecules is disordered, causing the penetration rate of the liquid crystal to change. When the external force is removed, mura still remains on the screen, leading to the quality defect of frame retention.